Needling loom with elliptical type movement, table for such a needling loom and manufacturing method of such a table

ABSTRACT

Needle machine comprising at least one needle plate, from which projects an array of needles, means for imparting an elliptical, reciprocating motion to the needles and at least one support table drilled with an array of through holes, or which it is intended to pass in a direction MD, being supported on it, a fabric or web of fibres to be consolidated by needling, the each executing an elliptical, reciprocating motion in the respective through holes, each having an upper respective opening on the fabric support side, a lower respective opening on the opposite side and an inner sidewall extending between the two upper and lower openings, characterised in that each hole is machined so that there is a longitudinal section with a greater dimension MD in which the upper respective opening of the hole has a greater dimension in the direction MD and, in this longitudinal section of greater dimension MD, the inner sidewall of the hole is defined, at least in its upper region, by two left and right lines inclined to the vertical and converging downwards, the angles of inclination of the two lines to the vertical being of opposite sign and in particular each having an absolute value of between 2 and 30° respectively, in particular having the same absolute value.

The present invention relates to a needling device, or needle machine,comprising at least one needle plate whose needles are driven by a drivemechanism that imparts a so-called elliptical motion to the needles andat least one table to support a web of fibres, in particular non-woven,passing in front of the needles in a direction MD to be needled toconsolidate it, the table being drilled with an array of holes throughwhich the needles reciprocate after passing through the web of fibres tobe consolidated supported by the table.

The present invention also relates to a table and/or a strippercomprising an array of through holes for use in a needle machine of thistype.

Needle machines are already known from the prior art, for example fromFR-A1-2909104, in the name of the applicant, with elliptical motioncomprising a table drilled with an array of circular, cylindrical holes,through which pass needles with a horizontal component of motion MD, inparticular an elliptical motion, the needles not only moving vertically,perpendicular to the plane of the web passing in front of them, but alsohaving a component of motion in the direction MD.

Due to the vertical and horizontal motion of the needles, the circular,cylindrical holes must have a large diameter to allow the needles topass downwards and then upwards through the holes, in spite of theirelliptical motion. The density of the holes, and therefore the densityof the needles, is therefore limited meaning that the needling cannotachieve such good consolidation as one would desire or if, in spite ofeverything a table is made with a high needle density, the table becomesfragile due to the high proportion of drilling in relation to thematerial around the holes.

A needle machine is known from DE 43 20 035-A1 that has a needle plateand a support table drilled with an array of through holes, the throughholes being slotted with several needles passing through the sameslotted hole with a vertical up and down motion.

Needle machines are also known from FR 2 817 562-A1 and FR 2 738 846-A1according to the preamble of claim 1.

The present invention aims to overcome these problems of the prior artby proposing a table drilled with holes for a needling device, or needlemachine, as well as a needling device, or needle machine of the typewith elliptical motion, which improves the quality of the needling, inparticular by increasing the density of the holes without adverselyaffecting the overall strength of the drilled table.

According to the invention, a needle machine is as defined in claim 1.

Preferably, the edge of the upper opening is in the form of a slot,meaning that, in the horizontal plane parallel to the direction CD andto the direction MD or the horizontal plane CD-MD, it has a greaterdimension in the direction MD and greater than the greatest dimension inthe direction CD.

Preferably, the edge of the lower opening is in the form of a slot,meaning that, in the horizontal plane CD-MD, it has a greater dimensionin the direction MD and greater than the largest dimension in thedirection CD.

According to a preferred method of implementation, the edge of the upperopening and/or the edge of the lower opening, in the horizontal plane,that is in the plane parallel to the direction MD and to the directionCD, consist(s) of two circular arcs, or quasi circular arcs, inparticular of the same radius, each subtending an angle greater than180° but lower than 360°, with the distance between the two centreslower than the sum of their two radii, in particular less than doublethe radius in the case where they have the same radius, so as to form aFIG. 8.

According to another preferred method of implementation, the edge of theupper opening and/or the edge of the lower opening viewed from above,that is projected onto the horizontal plane, or the plane parallel tothe direction MD and to the direction CD, has or have the shape of aslot comprising two ends in the form of semi-circular arcs, or quasisemi-circular arcs, of the same radius, linked by two straight sections,in particular mutually parallel in the direction MD.

According to one preferred and advantageous method of implementation,making the table and or stripper very compact, with many holes, inparticular a majority of holes, preferably essentially all the holes,still more preferably each hole, is machined so that there is alongitudinal section with a greater dimension MD in which the respectiveupper opening of the hole is greatest in the direction MD and, on thelongitudinal section with the largest dimension MD, of the innersidewall of the hole is defined, at least in its upper region, by twoleft and right lines inclined to the vertical and converging downwards,the angles of inclination of the two lines to the vertical being ofopposite sign and in particular each has an absolute of between 2 and30° respectively, in particular has the same absolute value.

Preferably, in the longitudinal section with the greater dimension MD,the inner sidewall is defined by an upper right line, a lower rightline, a lower left line and an upper left line, the upper left and rightlines each being inclined to the vertical and converging downwards, thelower left and right lines each being inclined to the vertical, andconverging upwards, the upper left line being parallel to the lowerright line and the lower left line being parallel to the upper rightline.

Preferably, the angles of inclination to the vertical of the lowerright, lower left, upper right and upper left lines are equal to eachother in absolute value, in particular between 2° and 15°, so that atleast in the larger longitudinal section MD, the wall is essentiallysymmetrical with respect to the vertical plane CD, in particularsymmetrical with respect to the vertical plane CD.

Preferably, the points where the upper left line and the lower left lineand the lower right line and the upper right line respectively join areessentially half way between the two upper and lower openings, inparticular half way between the two upper and lower openings.

By thus providing a wider section either of a V shape in the case of atable of small thickness, or an X shape in the case of a thicker table,during manufacture of the drilled support table, less material isremoved, in particular drilling of the table is limited to those placesat which the needles must be allowed to pass, enabling the drilledproportion table to be limited, thereby permitting the holes to becloser together without adversely affecting the overall strength of thetable, and increasing the density of the holes and therefore the needlesand consequently the efficiency of the needling.

According to one method of implementation, the support table is flat inthe horizontal plane.

According to another method of implementation, the support table iscurved in the vertical plane MD, in particular circular, cylindrical, inparticular with a large radius of curvature with respect to thethickness of the table, in particular a radius/thickness ratio ofbetween 10 and 100, in particular between 20 and 50.

According to a preferred method of implementation, a drilled plateforming a stripper could be provided, situated above the web ornon-woven fabric to be consolidated, the stripper comprising throughholes, that may be holes according to the invention or circular,cylindrical holes.

The present invention also relates to a process of manufacturing a tablewith holes according to the invention, that consists of stages in whicha table is taken and an array of through holes is formed in it using atleast one circular, cylindrical drill, each circular, cylindrical drillapproaching the material, in particular the metal sheet, of the tablewith its axis inclined to the vertical to the table, or inclined to thenormal to the tangent in the case of a circular, cylindrical table,first drilling through the table, then approaching again at an inclinedangle of opposite sign to the previous angle to drill a second throughhole in the table, the second approach being displaced from the firstdrilling.

The present invention also relates to another process of manufacturing atable with holes according to the invention, consisting of stages inwhich a table is taken and an array of through holes is drilled in itusing at least one circular, cylindrical drill, each circular,cylindrical drill approaching the material, in particular the metalsheet, of the table with its axis inclined to the vertical to the table,or inclined to the normal to the tangent in the case of a circular,cylindrical table, first drilling through the table, the drill is chasedin the material to a position inclined at an opposite angle to the firstdrilling to produce the final hole.

The present invention also relates to a drilled support table, flat orcurved, in particular cylindrical, for a needle machine, as defined inclaim 10.

Preferably, the edge of the upper opening is in the form of a slot, thatis, in the horizontal plane parallel to the direction CD and thedirection MD or the horizontal plane CD-MD, has a greater dimension inthe direction MD than in the direction CD and/or the edge of the loweropening is in the form of a slot, that is, in the horizontal planeparallel to the direction CD and to the direction MD or the horizontalplane CD-MD, is greater in the direction upper MD at the widest part inthe direction CD.

Preferably, the edge of the upper opening and/or the edge of the loweropening, in the horizontal plane, that is in the plane parallel to thedirection MD and to the direction CD, consist(s) of two circular arcs orquasi circular arcs, in particular of the same radius, each subtendingan angle greater than 180° but less than 360°, with the distance betweenthe two centres less than the sum of their two radii, in particular lessthan double the radius in the case where they have the same radius,forming a figure-8.

In particular, a number of holes, in particular the majority of holes,preferably essentially all the holes, even more preferably each hole ismachined so that it has a longitudinal section with a greater dimensionMD in which the respective upper opening of the hole is greater in thedirection MD and, in this longitudinal section of greater dimension MD,the inner sidewall of the hole is defined, at least in the upper region,by two left and right lines inclined to the vertical and convergingdownwards, the angles of inclination of the two lines to the verticalbeing of opposite sign and in particular each has an absolute value ofbetween 2 and 30° respectively, in particular of the same absolutevalue.

Preferably, the table is curved, in particular in a circular,cylindrical shape, in the vertical plane MD.

The present invention also relates to a flat or curved stripper, inparticular cylindrical, drilled for a needle machine, as defined inclaim 10.

Preferably, the edge of the upper opening is in the form of a slot, thatis, in the horizontal plane parallel to the direction CD and to thedirection MD or the horizontal plane CD-MD has a greater dimension inthe direction MD than in the direction CD and/or the edge of the loweropening is in the form of a slot, that is, in the horizontal planeparallel to the direction CD and to the direction MD or the horizontalplane CD-MD, has a greater dimension in the direction MD than thegreatest dimension in the direction CD.

Preferably, the edge of the upper opening and/or the edge of the loweropening, in the horizontal plane, that is in the plane parallel to thedirection MD and to the direction CD, consist(s) of two circular arcs orquasi circular arcs, in particular of the same radius, each subtendingan angle greater than 180° but less than 360°, with the distance betweenthe two centres less than the sum of their two radii, in particular lessthan double the radius in the case where they have the same radius,forming a figure-8.

In particular, a number of holes, in particular the majority of theholes, preferably essentially all the holes, even more preferably eachhole is machined so that there is a longitudinal section of greaterdimension MD in which the respective upper opening of the hole a isgreater in the direction MD and, in this longitudinal section of graterdimension MD, the inner sidewall of the hole is defined, at least in theupper region, by two left and right lines inclined to the vertical andconverging downwards, the angles of inclination of the two lines to thevertical being of opposite sign and in particular each has an absolutevalue of between 2 and 30° respectively, in particular having the sameabsolute value.

Preferably, the stripper is curved, in particular of circular,cylindrical shape, in the vertical plane MD.

As an example, a preferred method of implementation of the inventionwill now be described with reference to the drawings in which:

FIG. 1 is a general view of a needle machine according to the invention;

FIG. 2 is a longitudinal, cross-sectional view (that is in the verticalplane in the direction MD) of part of the drilled table and someneedles;

FIG. 3 is a perspective view of a hole formed in the support table inFIG. 2 according to one method of implementation of the invention;

FIG. 4 is a view from above of the hole in FIG. 3;

FIG. 5 is a longitudinal, cross-sectional view of the greater dimensionMD of the hole in FIGS. 3 and 4 (this is the cross-section on A-A inFIG. 4);

FIG. 6 is a perspective view of another method of machining a hole inthe support table;

FIG. 7 is a view from above the hole in FIG. 5; and

FIG. 8 is a longitudinal, cross-sectional view of the greater dimensionMD of the hole in FIGS. 6 and 7 (this is the cross-section on A-A inFIG. 7).

FIG. 1 shows a needle machine according to the invention. The needlemachine comprises a plate 1 with needles 2 and means for imparting anelliptical motion to the machine 1 with needles 2, meaning that thepoint of the needle follows an elliptical path with one component of itsmotion vertical and one component in the direction MD.

This type of needle machine with elliptical motion is well known in thefield and the control mechanism will not be described in further detailhere. If desired, one could refer to FR-A1-2909104 for a more completedescription of a method of implementation of such a needle machine.

The needle machine in FIG. 1 comprises a support table 3 in which fourthrough holes have been drilled. The table is shown in FIG. 1 supportinga web or mat of fibre (F) passing from left to right in front of theneedles in FIG. 1, this direction being called the direction MD (MachineDirection or Direction Machine), that is, the direction in which the webmoves while supported by the support table.

A stripper could also be provided (not shown in the diagrams), namely adrilled plate, positioned above the non-woven web that is traversed bythe reciprocating needles. The stripper may have identical holes tothose in the support table.

In addition, the support table is shown in FIG. 2 in the form of acircular support table with a large radius of curvature, the concaveside of the table facing towards the needle plate. However, according toanother method of implementation, one could also provide a flat supporttable with a straight section, arranged horizontal or inclined to thehorizontal.

The holes 4 are machined in a form that could be as shown in FIGS. 2 to5.

Each hole extends from the upper surface of the table to the lowersurface, terminating with two upper lower openings 5 and 6 respectively.The sidewall 7 of the hole extends between openings 5 and 6. FIG. 4shows a view from above of the hole 4. The opening edge 5 consists oftwo sections, left 8 and right 9 respectively, in circular arcs eachsubtending an angle of over 180°, for example 270°, with preferably thesame radii, but whose centres are spaced apart by a distance less thanthe sum of the two radii so it is shaped liked a FIG. 8. One could alsodefine the longitudinal cross section of greater width in the directionMD of the hole as in cross-section A-A, which corresponds to the greaterdimension L of the opening 5. This section corresponds to thecross-section in the longitudinal plane, that is the plane comprisingthe direction MD and the vertical direction and passing by the straightline linking the two points furthest from the edge of the opening 5. Thecross-section in this plane of greater length is shown in FIG. 2. Thesidewall 7 is defined here by the four lines, upper right 10, upper left11, lower left 12 and lower right 13, respectively.

Above was described the fact that the two sections 8 and 9 in circulararcs have the same radius. However, according to the invention, circulararcs of different radii could still be provided.

As shown in FIG. 2, the lengths of the four lines 10, 11, 12 and 13could be made the same. However, one could also have different lengths,in particular different lengths between the upper and lower and lines.

Lines 10 and 11 are inclined to the vertical axis by respective anglesof opposite signs and absolute values of between, for example, 2° and15°, preferably between 5° and 10°, so that these two lines convergedownwards. The two angles could have the same absolute value, as shown,or have different values. Lines 12 and 13 are inclined to the verticalaxis by respective angles of opposite sign and with absolute values ofbetween, for example, 2° and 15°, preferably between 5° and 10°, so thatthese two lines converge upwards. The two angles could have the sameabsolute value, as shown, or different values.

The inclinations with respect to the vertical axis 14 of the lines 10,11, 12 and 13 of the hole may preferably be such that line 12 isparallel to line 10 and line 13 is parallel to line 11.

FIGS. 6 to 8 show another possible method of machining the holesaccording to the invention. FIG. 7 shows the edge of the upper opening5′ of a hole machined in this way. Each hole extends from the uppersurface of the table to the lower surface, terminating in two openings,upper 5′ and lower 6′ respectively. The sidewall 7′ of the hole extendsbetween openings 5′ and 6′. The edge of the opening 5′ has two sections,left 18 and right 19 respectively, in circular arcs of the same radiusand each subtending an angle of 180°. The two semicircular sections 18and 19 are separated by two parallel straight sections 20 and 21extending in the direction MD, so that the edge of the upper opening isin the form of a slot. One can then define the greatest longitudinalcross-section in the direction MD of the hole according to thecross-section A-A′, which corresponds to the greater dimension L′ of theopening 5′. This cross-section corresponds to that in the longitudinalplane, that is the plane comprising the direction MD and the verticalpassing the straight line linking the two points of the edge of theopening furthest from each other 5′. The greater cross-section in thisplane is shown in FIG. 8. The sidewall 7′ is here defined by four lines,upper right 10′, upper left 11′, lower left 12′ and lower right 13′respectively.

As shown in FIG. 8, the lengths of the four lines 10′, 11′, 12′ and 13′can be made the same. However, they could also be of different lengths,in particular different lengths between the upper lines and the lowerlines.

Lines 10′ and 11′ are inclined to the vertical axis by respective anglesof opposite sign and with absolute values of between, for example 2° and15°, preferably between 5° and 10°, so that the two lines convergedownwards. The two angles can be made the same absolute value, as shown,or of different values. Lines 12′ and 13′ are inclined to the verticalaxis at respective angles of opposite sign and absolute values ofbetween, for example between 2° and 15°, preferably between 5° and 10°,so that the two lines converge upwards. The two angles can be made thesame absolute value, as shown, or they may have different values.

The inclinations to the vertical axis 14′ of the hole of the lines 10′,11′, 12′ and 13′ may preferably be such that line 12′ is parallel toline 10′ and line 13′ is parallel to line 11′.

In the two methods of implementation the shape of the upper openings 5,5′ respectively is described in FIGS. 3 to 5 and 6 to 8. It should benoted that in these two methods of implementation, the lower openings 6and 6′ have the same shape and size as those described for the upperopenings. In addition, a single needle only passes through one hole attime.

According to other methods of implementation, however, holes could haveupper and lower parts that are not symmetrical in relation to the medianplane, as well as upper and lower openings of different sizes. This isthe case when the holes are machined in a circular, cylindrical table,owing to the curvature of the plate. Depending on the thickness of thetable and the position of the plane separating the upper and lower linesfrom the inner sidewall, there could also be upper and lower openings ofdifferent shapes. There could also be a sidewall with only the upper (orlower) region described above, that is with a longitudinal cross-sectionwith a greater dimension MD with only two upper (or lower) left andright lines inclined with respect to each other, that is holes of V orinverted V cross-section and not X as described in the diagrams.

A manufacturing process for a table with holes as described in FIGS. 3to 5, consists in taking a plate, for example of steel, flat or curved(in particular circular, cylindrical or part circular, cylindrical) andforming in it an array of through holes 4 using a circular, cylindricaldrill, the circular, cylindrical drill approaching the material, inparticular the steel sheet, of the table with its axis inclined to thevertical of the table, or inclined to the normal to the tangent in thecase of a circular, cylindrical table, to drill the first through holesin the table, another approach is then made, with same drill or adifferent drill, in particular of different radius, at an inclined angleof opposite sign to the previous angle to drill a second array ofthrough holes in the table, the said other approach being at a distancefrom the first drilling, but however having a common region with itthereby producing a hole with a shape according to the method ofimplementation shown in FIGS. 3 to 5.

Another manufacturing process for a table with holes according to FIGS.6 to 8, consists in taking a plate, for example of steel, flat or curved(in particular circular, cylindrical or in part circular, cylindrical)and forming in it the array of through holes 4′ using a circular,cylindrical drill, the circular, cylindrical drill approaching thematerial, in particular the steel sheet, of the table with its axisinclined to the vertical of the table, or inclined to the normal to thetangent in the case of a circular, cylindrical table, to drill the firstthrough holes in the table, then chasing the drill in the material up toan inclined position of opposite sign to the inclination of the firstdrilling thereby producing the final hole with a shape according to themethod of implementation shown in FIGS. 6 to 8.

In the methods of implementation shown in the diagrams, the greaterdimension (L or L′) in the direction MD of the edges of the upper andlower openings is greater than the largest dimension in the direction CD(This dimension is equal to the radius (or to the greater of the tworadii in the case of a non-symmetrical eight) of the circular arcsforming the eight or to the radius of the two semi-circles of the slot).

The invention claimed is:
 1. A needle machine comprising at least oneplate, from which projects an array of needles, means for imparting anelliptical, reciprocating motion to the needles, and at least onesupport table drilled with an array of through holes, over which afabric or a web of fibers is intended to pass in a direction MD, theneedles having a reciprocating motion following the elliptical motion inthe respective through holes, each hole having an upper respectiveopening in a side of the support table, a lower respective opening in anopposite side of the support table and an inner sidewall extendingbetween the upper and lower openings, characterized in that at least onehole is machined so that in a greater MD dimension longitudinal section,the upper respective opening of the hole has a largest dimension in thedirection MD and, in this said greater MD dimension longitudinalsection, the inner sidewall of the hole is defined, starting from theupper opening, by left and right lines inclined to the vertical andconverging downwards, angles of inclination of the two lines to thevertical being of opposite sign, and the support table consisting ofsteel.
 2. The needle machine according to claim 1, characterized in thatan edge of the upper opening is in the form of a slot, that is, in ahorizontal plane parallel to a direction CD and to the direction MD, orhorizontal plane CD-MD, has a largest dimension in the direction MDgreater than the largest dimension in the direction CD and/or an edge ofthe lower opening is in the form of a slot, that is, in a horizontalplane parallel to the direction CD and to the direction MD, orhorizontal plane CD-MD, has a largest dimension in the direction MDgreater than the largest dimension in the direction CD.
 3. The needlemachine according to claim 2, characterised in that the edge of theupper opening and/or the edge of the lower opening, in the horizontalplane CD-MD is/are in the form of a slot, comprising two ends in theform of quasi semicircular arcs, linked together by two straightsections.
 4. The needle machine according to claim 1, characterized inthat a cross section of the support table in a plane comprising the MDdirection and the vertical direction is curved.
 5. The needle machineaccording to claim 1, characterized in that the angles of inclination ofthe two lines to the vertical each have an absolute value of between 2°and 30°.
 6. The needle machine according to claim 1, characterized inthat the angles of inclination of the two lines to the vertical have asame absolute value.
 7. The needle machine according to claim 2, whereinthe edge of the upper opening and/or the edge of the lower opening, inthe horizontal plane CD-MD, consist(s) of two circular arcs, or quasicircular arcs, each subtending an angle of greater than 180° but lessthan 360°, where a distance between the two centers of the arcs is lessthan the sum of their two radii.
 8. The needle machine according toclaim 1, wherein in the said greater MD dimension longitudinal section,the inner sidewall is defined by an upper right line, a lower rightline, a lower left line and an upper left line, the upper right and leftlines each being inclined to the vertical and converging downwards, thelower right and left lines each being inclined to the vertical andconverging upwards, the upper left line being parallel to the lowerright line and the lower left line being parallel to the upper rightline.
 9. A needle machine comprising at least one plate, from whichprojects an array of needles, means for imparting an elliptical,reciprocating motion to the needles, and at least one support tabledrilled with an array of through holes, over which a fabric or a web offibers is intended to pass in a direction MD, the needles having areciprocating motion following the elliptical motion in the respectivethrough holes, each hole having an upper respective opening in a side ofthe support table, a lower respective opening in an opposite side of thesupport table and an inner sidewall extending between the upper andlower openings, wherein at least one hole is machined so that in agreater MD dimension longitudinal section, the upper respective openingof the hole has a largest dimension in the direction MD and, in thissaid greater MD dimension longitudinal section, the inner sidewall ofthe hole is defined, at least in an upper region, by left and rightlines inclined to the vertical and converging downwards, angles ofinclination of the two lines to the vertical being of opposite sign, anedge of the upper opening is in the form of a slot, that is, in ahorizontal plane parallel to a direction CD and to the direction MD, orhorizontal plane CD-MD, has a largest dimension in the direction MDgreater than the largest dimension in the direction CD and/or an edge ofthe lower opening is in the form of a slot, that is, in horizontal planeparallel to the direction CD and to the direction MD, or horizontalplane CD-MD, has a largest dimension in the direction MD greater thanthe largest dimension in the direction CD, characterized in that theedge of the upper opening and/or the edge of the lower opening, in thehorizontal plane CD-MD, consist(s) of two circular arcs, or quasicircular arcs, each subtending an angle of greater than 180° but lessthan 360°, where a distance between the two centers of the arcs is lessthan the sum of their two radii.
 10. The needle machine according toclaim 9, characterized in that a distance between the two centers isless than double the radius in the case where they are of the sameradius, to form a FIG. 8 shape.
 11. A needle machine comprising at leastone plate, from which projects an array of needles, means for impartingan elliptical, reciprocating motion to the needles, and at least onesupport table drilled with an array of through holes, over which afabric or a web of fibers is intended to pass in a direction MD, theneedles having a reciprocating motion following the elliptical motion inthe respective through holes, each hole having an upper respectiveopening in a side of the support table, a lower respective opening in anopposite side of the support table and an inner sidewall extendingbetween the upper and lower openings, wherein at least one hole ismachined so that in a greater MD dimension longitudinal section, theupper respective opening of the hole has a largest dimension in thedirection MD and, in this said greater MD dimension longitudinalsection, the inner sidewall of the hole is defined, at least in an upperregion, by left and right lines inclined to the vertical and convergingdownwards, angles of inclination of the two lines to the vertical beingof opposite sign, characterized in that, in the said greater MDdimension longitudinal section, the inner sidewall is defined by anupper right line, a lower right line, a lower left line and an upperleft line, the upper right and left lines each being inclined to thevertical and converging downwards, the lower right and left lines eachbeing inclined to the vertical and converging upwards, the upper leftline being parallel to the lower right line and the lower left linebeing parallel to the upper right line.
 12. The needle machine accordingto claim 11, characterized in that the angles of inclination to thevertical of the lower right, lower left, upper right and upper leftlines are equal to each other in absolute value, so that at least in thelongitudinal section with the greater dimension MD, the wall isessentially symmetrical in relation to the vertical plane CD.
 13. Theneedle machine according to claim 11, characterized in that points wherethe upper left line and the lower left line and the lower right line andthe upper right line respectively join, are essentially half way betweenthe two upper and lower openings.